The suction efficiency of a vacuum cleaner is determined, besides by the effective power of the electric motor, also to a large extent by the suction effect losses or air flow losses in the air passages through the vacuum cleaner.
Avoiding air flow losses in the air passages is important in all kinds of vacuum cleaners in order to achieve a high suction efficiency and reduce energy consumption. However, it is especially important in vacuum cleaners having an electrical motor powered by batteries. In such a case it is not a preferred option to compensate for air flow losses in the air passages by increasing the motor power, since this will have the effect that the battery power will be used up in a shorter time, necessitating more frequent recharging. As an alternative, the battery power capacity could be increased by providing more batteries in the vacuum cleaner, but this will have the effect that the costs and the weight of the vacuum cleaner also will increase.
Battery powered vacuum cleaners are known in many different embodiments. The most common type of battery powered vacuum cleaners are small hand held units used for easy cleaning of kitchens, motor cars and the like. Due to the battery operation, which eliminates the need for connecting a mains supply cable, it is possible to perform, for example, daily cleaning of a kitchen swiftly and easily. There are also known battery powered vacuum cleaners of a stick-formed type, having a nozzle device in a lower end and a handle in an upper end, by means of which it is possible to vacuum clean floors for example. There are also known battery powered vacuum cleaners being a combination of these two types, that is, a so called 2-in-1 vacuum cleaner comprising a hand held unit which optionally can be inserted into an elongated support body to form a stick-type vacuum cleaner having a nozzle device in a lower end and a handle in an upper end, by means of which, for example, floors easily can be vacuum cleaned, whereas the hand held unit also can be used separately to vacuum clean, for example, tables, worktops or narrow spaces. In this latter type of vacuum cleaner, all of the machinery, such as the motor, fan unit, batteries and debris collector, is positioned inside the comparatively small hand held unit, whereas the support body only functions as a carrier for the hand held unit when vacuum cleaning floors. As a consequence, the available space for the machinery is limited at the same time as the air must be drawn a comparatively long distance from the nozzle device in the lower end of the support body, through the air passages inside the same, and through the hand held unit.